The invention relates to a gas guide system for a periphery of an internal combustion engine comprising: an upstream gas supply structure for supplying gas to the internal combustion engine, a downstream guide structure including an exhaust gas treatment system for conducting gases away from the engine and a first gas outlet structure for the removal of a first partial gas stream from at least one cylinder of a first group of cylinders and also a second gas outlet structure for the removal of a second partial gas stream from at least one cylinder of a second group of cylinders, wherein, in case of a partial operation of the internal combustion engine, that at-least one cylinder of the first group of cylinders is designed for operation with fuel injection and the at-least one cylinder of the second group of cylinders is designed for operation without fuel injection. The Invention further resides in a combustion power generation system including a combustion engine with a gas guide system arranged in the periphery of the engine for guiding the gas through the engine. Furthermore, the present invention resides in a method for operating a combustion power plant with a gas guide system for the periphery of the combustion power plant for guiding gas to and from the power plant, comprising the steps of: supplying as to a supply side of the combustion power plant, conducting gas away from the combustion power plant via an exhaust gas treatment system, removing a first partial gas stream from at least one cylinder of a first group of cylinders, and removing a second partial gas stream from at least one cylinder of a second group of cylinders wherein, during a partial operation of the combustion power plant, the at least one cylinder of the first group of cylinders is operated with fuel injection and the at least one cylinder of the second group of cylinders is operated without fuel injection.
Such a method for the operation of a combustion power plant, such as an engine and, in particular, a large diesel engine may include a gas guide system for the periphery of the engine as referred to initially. For example, under low load or in idle, an engine may be operated partially wherein the fuel injection into some cylinders or cylinder groups, for example, a whole cylinder bank, may be shut down. This partial engine operation is also designated as ZA operation (cylinder out). The cylinders not provided with fuel injection are also called non-fired or unfired cylinders. The cylinders provided with fuel injection are called fired cylinders. A cylinder designed for operation with fuel injection includes an injector which is operative during full and partial engine operation for the injection of fuel. A cylinder designed for operation without fuel injection includes an injector which is controlled to inject fuel during full engine operation but to inject no fuel during partial engine operation. The partial operation of the engine has the advantage that, for the same effective power output of the engine, correspondingly more fuel is injected into the fired cylinders so that the same effective power output is achieved as with full engine operation. During the full engine operation all the cylinders of the engine are fired that is fuel is injected into all cylinders.
During partial engine operation, the temperature of the exhaust gas reaching the exhaust gas treatment system differs from the exhaust gas temperature during full engine operation because the hot exhaust gas from the fired cylinders is mixed with comparatively cold gas—actually comparatively cold compressed air—of the unfired cylinders. In modern Diesel engines equipped with a conventional exhaust gas guide structure, it has in particular been found that, during idle or low load operation, that is, during partial load operation, the exhaust gas temperature is too low for an effective exhaust gas treatment. As a result of the mixing of the hot exhaust gas of fired cylinders and comparatively cold exhaust gas of the non-fired cylinders, the exhaust gas temperature is actually so low that the downstream exhaust gas treatment system is not sufficiently hot to be effective during partial engine operation.
An exhaust gas treatment system may include for example a particle filter (PDF) called also a soot particle filter (RPF) or a Diesel particle filter (DPF) and in particular a catalytically reactive particle filter (CPF). Such particle filter operate for example according to the CRT principle (CRT=Continuous Regeneration Trap). Catalytically or otherwise regenerated particle filters (PF) require for the regeneration generally a certain minimum temperature. Similar minimum temperature requirements exist for catalytic converters used in exhaust gas treatment systems, for example, for oxidation catalytic converters, SCR catalytic converters (Selective Catalytic Reaction), three-way catalysts, NOx storage catalysts or other similar suitable vehicle catalytic converters.
It is desirable to keep the exhaust gas temperature in the exhaust gas treatment systems sufficiently high also during partial engine operation so that its effectiveness is increased without an increase in fuel consumption.
Conventional technical measures increase the temperature in the exhaust gas treatment systems actively in order to increase the effectiveness of the exhaust gas treatment systems.
DE 10 333 933 A1, for example, discloses a method and an arrangement for controlling an internal combustion engine wherein the emissions of the combustion engine in the exhaust gas are detected. Depending on the comparison of the detected emissions with a desired value, a control value pertinent to the combustion in the combustion engine is corrected. The control valve is for example the air flow volume to the engine. Such a supply air side throttling of the engine usually results in a noticeably increased fuel consumption and a reduced power output of the engine.
DE 42 39 357 C1 discloses a method for the thermal regeneration of a particle filter for the exhaust gas of a Diesel engine wherein, during partial load operation, the exhaust gas temperature is increased by heating using electrical energy to such a degree that auto-ignition of the combustible exhaust gas components collected in the particle filter is achieved. Such a method however results in an increased fuel consumption.
DE 36 05 255 discloses a method for the regeneration of exhaust gas filter systems wherein the cylinder or, respectively, group of cylinders to which the particle filter to be regenerated is assigned is supplied with the amount of fuel or fuel air mixture needed for the regeneration of the filter. Such a method uses for example retarding of the main fuel injection or one or several follow-up injections by which the exhaust gas temperature is increased but also the fuel consumption is noticeably increased. A late engine internal fuel injection may also cause fuel to reach the engine oil and thereby detrimentally affect the engine lubrication.
It would be desirable if the disadvantages of the state of the art, particularly an increase of the fuel consumption and/or the danger of a fuel seepage into the engine oil could be limited. But it should still be possible to provide for a reliable and, comparatively, simple exhaust gas treatment in an exhaust gas treatment system of an engine.
It is therefore the object of the present invention to provide a gas guide system, a combination engine system, and a method for operating a combustion engine system with a gas guide system for the periphery of a combustion engine, with improved exhaust gas treatment capability. In particular, the improvement should result in a reliably operating exhaust gas treatment system also during partial engine operation, preferably by keeping the exhaust gas temperatures comparatively high during partial engine operation. Specifically, the exhaust gas treatment system should be capable of operating as effectively as possible also during partial engine operation.